WO2005078644A1

WO2005078644A1 - Radio frequency identity tag for reducing power consumption

Info

Publication number: WO2005078644A1
Application number: PCT/KR2004/000541
Authority: WO
Inventors: Byounghwan Choi
Original assignee: Sdsystem Co. Ltd
Priority date: 2004-02-13
Filing date: 2004-03-16
Publication date: 2005-08-25
Also published as: KR100630898B1; KR20050081503A

Abstract

A power-saving radio frequency identity (RF ID) tag is provided, which includes a vibration sensor (120A) for detecting vibration of the RF ID tag, a vibration signal generator (120B) for generating a vibration signal based on the vibration detected by the vibration sensor (120A), a vibration discriminator (130) for generating a movement discrimination signal for discriminating movement of a user who uses the RF ID tag according to an output waveform of the vibration signal output from the vibration signal generator (120B), and a controller (170) which controls a power supply (110) to apply power to a RF circuit (140) according to the movement discrimination signal output from the vibration discriminator (130).

Description

RADIO FREQUENCY IDENTITY TAG FOR REDUCING POWER CONSUMPTION

Technical Field The present invention relates to a radio frequency identity (RF ID) tag, and more particularly to, a power-saving RF ID tag for reducing power consumption which detects movement of a user who uses a RF ID tag and enables a RF circuit to operate at a transceiver mode only when the user moves, to thereby control the RF ID tag to execute communications.

Background Art In general, a radio frequency identity tag (which is referred to as a RF ID tag) uses radio frequency and exchanges information with a tag reader on a wireless basis. The RF

ID tags are widely applied and used in traffic cards for subway and bus, which are called smart tags or smart labels. Such a RF ID tag has a merit of processing information quickly wirelessly in comparison with a bar code system containing information in a striped image. The RF ID tag technology has been developed into a degree that information can be read immediately within a certain distance. Also, a read/write (RAV) terminal processes information at a speed or 100ms or so, and thus a user who uses the RF ID tag need not stop or await until the RAV^" tag terminal completely processes the RF ID tag information. Also, the RF ID tag can be made as large as or compacter than the existing credit cards. Accordingly, the RD ID tag can be read even at a state where the

RF ID tag is carried in a purse, bag or pocket, which enables users to use the RF ID tag conveniently. Also, since data is encrypted during communications, an illegal use can be prevented. Hereinbelow, a conventional RF ID tag will be described with reference to FIG. 1. FIG. 1 is a block diagram schematically showing a conventional radio frequency identity (RF ID) tag. As shown in FIG. 1, the conventional RF ID tag is powered from a power supply 10 in the RF ID tag, and then a RF circuit 20 in the RF ID tag operates at a receiving mode. When high band frequency transmitted from the RAV terminal is received at an antenna 30 in the RF ID tag at a state where the RF ID tag has closely approached the RAV terminal, various information is transmitted from the RF ID tag to the RAV terminal according to execution of programs contained in a central controller 40 installed in the RF ID tag. However, since the RF circuit 20 in the conventional RF ID tag operates all the time at a receiving mode, power consumption becomes large to thus cause a battery to be replaced frequently. Also, since there is no function of selecting operational modes of the RF ID tag, data such as personal particular information or password which has been already stored cannot be corrected conveniently and thus it is difficult to re-use the RF ID tag. Also, a variety of services such as an opening and closing function of an entrance gate or door cannot be used at a state where the RF ID tag does not transmit or receive high band frequency smoothly with respect to the RAV terminal.

Disclosure of the Invention To solve the above problems, it is an object of the present invention to provide a power-saving radio frequency identity (RF ID) tag which detects movement of a user who uses an RF ID tag and enables a RF circuit to operate at a transceiver mode only in the case of spatial or positional movement of the user other than finite movement, to thereby prevent unnecessary power consumption. It is another object of the present invention to provide a power-saving radio frequency identity (RF ID) tag which enables a user to select or convert an operational mode of the RF ID tag, to thereby easily transmit information when correcting information or under the emergency situation. To accomplish the above object of the present invention, according to the present invention, there is provided a power-saving radio frequency identity (RF ID) tag comprising: a vibration sensor for detecting vibration of the RF ID tag; a vibration signal generator for generating a vibration signal based on the vibration detected by the vibration sensor; a vibration discriminator for generating a movement discrimination signal for discriminating movement of a user who uses the RF ID tag according to an output waveform of the vibration signal output from the vibration signal generator; and a controller which controls a power supply to apply power to a RF circuit according to the movement discrimination signal output from the vibration discriminator. Preferably, the vibration sensor comprises: a conductive hollow body whose both ends are opened; a conductive tap which is connected to both ends of the conductive body; a lead wire which extends from the outer end of the conductive tap to the inner end thereof while penetrating the conductive tap; and a conductive moving object which can be freely moved within a space formed by the conductive body and the conductive tap. Preferably, the vibration signal generator comprises: the lead wire grounded; a capacitor connected between the conductive body and the vibration discriminator; a first resistor connected between the conductive body and the power supply; and a second resistor connected between the power supply and the vibration discriminator.

Brief Description of the Drawings The above and other objects and advantages of the present invention will become more apparent by describing the preferred embodiment thereof in detail with reference to the accompanying drawings in which: FIG. 1 is a block diagram schematically showing a conventional radio frequency identity tag; FIG. 2 is a block diagram showing a power-saving radio frequency identity (RF ID) tag according to a preferred embodiment of the present invention; FIG. 3 shows a configuration of a vibration sensor and a vibration signal generator in the power-saving RF ID tag of FIG. 2; FIG. 4 is a waveform diagram showing the output of the vibration signal generator of FIG. 3; FIG. 5 is a schematic view showing a control system to which the power-saving RF ID tag of FIG. 2 is applied; and FIG. 6 is a block diagram schematically showing a control system to which the power-saving RF ID tag of FIG. 2 is applied.

Best Mode for Carrying out the Invention Hereinbelow, a power-saving radio frequency identity (RF ID) according to the present invention will be described with reference to the accompanying drawings. The like or same elements are assigned the like or same reference numerals all over the drawings, for convenience of explanation. Also, in the case that the detailed description of the relevant known functions or components may make the gist of the present invention unclear unnecessarily, the detailed description thereof will be omitted. FIG. 2 is a block diagram showing a power-saving radio frequency identity (RF ID) tag according to a preferred embodiment of the present invention. As shown in FIG. 2, a power-saving radio frequency identity (RF ID) tag according to a preferred embodiment of the present invention includes: a power supply 110 for supplying power for the RF ID tag 100; a vibration sensor 120 A for detecting movement of a user who wears or carries the RF ID tag 100; a vibration signal generator 120B for generating a vibration signal based on the vibration detected by the vibration sensor 120A; a vibration discriminator 130 for generating a movement discrimination signal for discriminating spatial or positional movement of the user according to the vibration signal output from the vibration signal generator 120B; a RF circuit 140 whose operational mode is converted into a transceiver mode when a vibration discrimination signal is output from the vibration discriminator 130; an antenna 150 which transmits or receives high band frequency with respect to a neighboring read/write (RAV) terminal (see FIGs. 4 and 5) when the operational mode of the RF circuit 140 is in a transceiver mode; an operational mode selector 160 provided with functional keys for altering an operational mode of the RF ID tag 100; and a controller 170 which includes a memory (not shown) and a central controller (not shown) which are electrically connected to each of the above-described components and which stores programs for executing the entire operations of the RF ID tag 100. FIG. 3 shows a configuration of a vibration sensor and a vibration signal generator in the power-saving RF ID tag of FIG. 2. As shown in FIG. 3, the vibration sensor 120A includes: a hollow body 121 whose both ends are opened; a tap 122 which is connected to both ends of the body 121; a lead wire 123 which extends from the outer end of the tap 122 to the inner end thereof while penetrating the tap 122; and a moving object 124 which can be freely moved within a space formed by the body 121 and the tap 122. Here, it is preferable that the hollow body 121, the lead wire 123 and the moving object 124 are made of a conductive material, respectively. The vibration signal generator 120B which is electrically connected to the power supply 110 and the vibration discriminator 130, in which the lead wire 123 is grounded. A capacitor "C" is disposed on the connection line which connects between the body 121 and the vibration discriminator 130. A resistor Rl which is connected to an end voltage Vcc of the power supply 110 is disposed on the connection line which connects between the body 121 and the capacitor "C." A resistor R2 which is connected to an end voltage V of the power supply 110 is disposed on the connection line which connects between the capacitor "C" and the vibration discriminator 130. Also, the vibration signal generator 120B functions as follows. When the moving object 124 contacts the tap 122 and thus the body 121 and the lead wire 123 are conducted (which will be referred to as a switch-on state), the voltage Ncc of the power supply 110 is grounded via the resistor Rl and the vibration sensor 120A, and the voltage V is charged into the capacitor "C" instantaneously via the resistor R2. Accordingly, the output from the vibration signal generator 120B becomes low. When the capacitor "C" is fully charged, the voltage N does not flow toward the capacitor "C" and thus the output from the vibration signal generator 120B becomes high. According to the capacity of the capacitor "C" the vibration signal generator 120B outputs differently. However, the output from the vibration signal generator 120B falls down to a low state instantaneously and then is maintained into a high state again. In the case that the vibration signal generator 120B maintains a conduction state, the output from the vibration signal generator 120B is also maintained into a high state. In the case that the moving object 124 moves and thus the body 121 is separated from the lead wire 123 (which will be referred to as a switch-off state), the voltage Vcc does not flow into the ground via the resistor Rl and is charged into the capacitor "C" and the voltage N is applied to the vibration signal generator 120B as a high signal. When the vibration signal generator 120B becomes in a switch-on state again, the output from the vibration signal generator 120B falls down to a low state instantaneously as described above, and then maintained into a high state again. That is, since the output from the vibration signal generator 120B falls from a high state down to a low state as soon as the state of the switch is changed, the output from the vibration signal generator 120B is output as a falling edge signal which falls from a high state down to a low state. Accordingly, a vibration signal is generated with respect to vibration detected by the vibration sensor 120 A. Thus, as shown in FIG. 4, when a user who carries the RF ID tag 100 moves by a certain spatial or positional distance, the vibration signal generator 120B outputs a continuous dense waveform as in a section "A" while when a user who carries the RF ID tag 100 does not move by a certain spatial or positional distance, the vibration signal generator 120B outputs a single sparse waveform as in a section "B." The vibration discriminator 130 receives the output waveform generated from the vibration signal generator 120B, that is, the number of vibrations, the change in the number of vibrations, the time of change in the number of vibrations from the vibration sensor 120A, and thus discriminates that a user who carries a RF ID tag 100 is in a moving section "A" if a continuous dense waveform is input as shown in FIG. 4, and he or she is in a stationary section "B" if a single sparse waveform is input. Meanwhile, the operational mode selector 160 is used to select an operational mode of the RF ID tag 100 and convert a current operational mode into the selected operational mode, and includes a correction button 162 and a transmission button 164. For example, when information such as personal particular data, password, system control data which is stored in a memory device of the RF ID tag 100 is corrected, the correction button 162 is selected so that an operational mode of the RF ID tag 100 is converted into a correction mode. As a result, the information is allowed to be corrected through encrypted communications with a RAV terminal. Accordingly, the re-use possibility of the RF ID tag 100 becomes high and information cannot be corrected. Meanwhile, the transmission button 164 is pressed so that the information can be transmitted for the RAV terminal under the special situation such as an emergency situation, an operational test of the RF ID tag 100, or a situation where positional or spatial movement of a user is not recognized by the vibration sensor 120A, the vibration signal generator 120B and the vibration discriminator 130. Accordingly, the operation mode of the RF ID tag 100 is converted into a transmission mode so that information can be easily transmitted. The function and effect of the power-saving RF ID tag according to a preferred embodiment of the present invention having the above-described configuration will be described below in detail with reference to FIGs. 5 and 6. FIG. 5 is a schematic view showing a control system to which the power-saving RF ED tag of FIG. 2 is applied, and FIG. 6 is a block diagram schematically showing a control system to which the power-saving RF ID tag of FIG. 2 is applied. As shown in FIGs. 5 and 6, if a user who carries an RF ID tag 100 approaches to an entrance gate or door of his or her company or home, the moving object 124 in the vibration sensor 120A contacts the tap 122 in the body 121 due to movement of the user, and thus the lead wire 123 and the body 121 are electrically conducted by the moving object 124. Accordingly, a high or low signal is input from the vibration signal generator 120B to the vibration discriminator 130. In this state, if vibration occurs again and thus the moving object 124 moves, the electrical conduction state formed between the lead wire 123 and the body 121 is released, and thus a low or high signal is input from the vibration signal generator 120B to the vibration discriminator 130. As a result, the vibration discriminator 130 discriminates existence of vibration through conversion between a low signal and a high signal which is input thereto, and thus recognizes a user's positional or spatial movement state (in a section "A" of FIG. 4). Thus, only when a signal indicating whether or not vibration occurs, that is, a vibration discrimination signal is output from the vibration discriminator 130, power necessary for operation of the RF ID tag 100 is supplied from the power supply 110. Then, when a vibration discrimination signal is output from the vibration discriminator 130, the operational mode of the RF circuit 140 is converted into a receiving mode by the controller 170, and thus receives high band frequency transmitted from the RAV terminal 210 which is installed in an entrance gate or door of the company or home, via the antenna 150. Then, the controller 170 controls the RF circuit 150 to operate at a transmission mode, so that the high band frequency including information such as personal particular data, password, system control data which is stored in a memory device (not shown) is transmitted to the RAV terminal 210 via the antenna 150. Thus, the RAV terminal 210 receives the high band frequency transmitted from the controller 170 and compares the received data with entrance permission data registered in a database of a central computer 200, to thereby judge whether he or she is allowed to enter the gate or door. If he or she is allowed to enter the gate or door in the result of judgement, an electrical signal for opening or closing the entrance gate or door is an entrance opening and closing system 310 which is electrically connected to the RAV terminal 210 is transmitted to open or close the entrance gate or door. Here, the RAV terminal 210 forms an aerial high frequency electric field for wireless communications via the antenna and is configured to be able to wirelessly communicate with the RF ID tag 100. Also, it is preferable that the RAV terminal 210 uses a plurality of antennas to collect information of RF ID tags 100 simultaneously and frequently from the entire space of the company or home. For example, the RAV terminal 210 may be connected to a lighting control system 320 and a cooler and heater control system 330 to control brightness of a corresponding light lamp and an operational temperature of a corresponding cooler and heater apparatus according to information stored in the RF ID tag 100. As described above, the power-saving RF ID tag according to the preferred embodiment of the present invention recognizes movement of a user who carries an RF ID tag 100 through the vibration sensor 120A, the vibration signal generator 120B and the vibration discriminator 130, and thus supplies power to the RF circuit 140 to operate at a transceiver mode. Thus, the RF ID tag 100 wirelessly communicates with the RAV terminal 210 only when the user who carries a RF ID tag 100 moves by a certain positional or spatial distance, to thereby prevent unnecessary power consumption. That is, when a user who uses a RF ID tag 100 does not move by a certain positional or spatial distance (in a section "B" of FIG. 4), RF communications are in a stationary state temporarily, and thus can reduce power consumption by avoiding a continuous RF communications. Also, when information such as personal particular data, password, system control data which is stored in a RF ID tag 100 is corrected, the correction button 162 in the operational mode selector 160 is pressed so that the RF ID tag 100 operates at a correction mode. Accordingly, the information can be corrected via encrypted communications with the RAV terminal 210 to thereby heighten a re-use possibility of the RF ID tag 100. Under the situation where a user's positional or spatial movement is not recognized by the vibration sensor 120A, the vibration signal generator 120B, and the vibration discriminator 130, or under an emergency situation, or, for example, in the case that brightness of a lighting system is controlled or a cooler and heater is controlled to control the room temperature to be an appropriate temperature, the transmission button 164 in the operational mode selector 160 is pressed so that the RF ID tag 100 operates at a transmission mode. Accordingly, control system setting data can be transmitted from the RAV terminal 210 to thereby control brightness of the lighting lamp or optimize the room temperature. As described above, the present invention has been described with respect to particularly preferred embodiment. However, the present invention is not limited to the above embodiment, and it is possible for one who has an ordinary skill in the art to make various modifications and variations, without departing off the spirit of the present invention.

Industrial Applicability As described above, the power-saving RF ID tag according to the present invention supplies power necessary for operation of the RF ID tag only when a user who carries the RF ID tag moves by a certain positional or spatial distance, to thereby reduce unnecessary power consumption. Also, the present invention can select a desired operational mode of an RF ID tag and convert a current operational mode into the selected operational mode to thereby correct information or transmit information compulsively under an emergency situation. As a result, the present invention can heighten a re-use possibility of the RF ID tag and can provide a variety of services such as control of brightness of lighting lamps or optimization of the room temperature.

Claims

What is claimed is: 1. A power-saving radio frequency identity (RF ID) tag (100) comprising: a vibration sensor (120 A) for detecting vibration of the RF ID tag (100); a vibration signal generator (120B) for generating a vibration signal based on the vibration detected by the vibration sensor (120A); a vibration discriminator (130) for generating a movement discrimination signal for discriminating movement of a user who uses the RF ID tag (100) according to an output waveform of the vibration signal output from the vibration signal generator (120B); and a controller (170) which controls a power supply (110) to apply power to a RF circuit (140) according to the movement discrimination signal output from the vibration discriminator (130).

2. The power-saving RF ID according to claim 1, wherein said vibration sensor (120 A) comprises: a conductive hollow body (121) whose both ends are opened; a conductive tap (122) which is connected to both ends of the conductive body (121); a lead wire (123) which extends from the outer end of the conductive tap (122) to the inner end thereof while penetrating the conductive tap (122); and a conductive moving object (124) which can be freely moved within a space formed by the conductive body (121) and the conductive tap (122).

3. The power-saving RF ID according to claim 2, wherein said vibration signal generator (120B) comprises: the lead wire (123) grounded; a capacitor (C) connected between the conductive body and the vibration discriminator (130); a first resistor (Rl) connected between the conductive body (121) and the power supply (110); and a second resistor (R2) connected between the power supply (110) and the vibration discriminator (130).